Food supplies in the flood-stricken area . We must act immediately before there’s none lef

问题补充：

Food supplies in the flood-stricken area . We must act immediately before there’s none left.

A. have run out

B. are running out

C. have been run out

D. are being run out

答案：

A. have run out

(答案→)B. are running out

C. have been run out

D. are being run out

解析：句意，在发生洪水的灾区食品供应即将用完。我们必须在全部用完之前采取行动。runout为不及物动词短语，不能使用被动形式，由此可排除C和D两个选项。A选项为现在完成时，原题中想要表达将要用完，还没有用完，所以不合题意，B选项为现在进行时态，可以表示将来，符合题意，故选B。